Field
Embodiments are directed to glass-ceramic substrates and more particularly to glass-ceramic substrates useful for Gallium Nitride (GaN) thin film growth.
Technical Background
Light emitting diodes (LEDs) have been commercialized for more than twenty years and have desirable attributes including energy efficiency, safety, small size, and long lifetime. Gallium nitride is a major material for LED manufacture.
Currently sapphire (Al2O3) and silicon are the typical materials used for LED substrates. Both have good chemical and thermal durability. However, sapphire is available in a limited quantity and in sizes smaller than 100 millimeters (mm) diameter, whereas silicon is available in sizes up to 300 mm in diameter. Furthermore, both materials differ significantly from GaN in their coefficient of thermal expansion (CTE). This mismatch results in substrate bow during growth and/or a high level of defects in the GaN crystal quality.
An alternative substrate with good CTE match to GaN, while also having good thermal stability (to 1100° C.), chemical durability, and surface polish characteristics would be advantageous.